/*
* 公共样式
*/
.flex
  display: flex
.flex-a
  display: flex
  align-items: center
.flex-a-c
  display: flex
  align-items: center
  justify-content: center
.flex-a-s
  display: flex
  align-items: center
  justify-content: start
.flex-a-e
  display: flex
  align-items: center
  justify-content: end